Idle problem after new cam, intake, head, etc
Thread Starter
Instructor
Joined: Apr 2004
Posts: 166
Likes: 4
From: Moneta, VA
Idle problem after new cam, intake, head, etc
Hi,
I have just completed a new engine build with:
L98 bottom end
Dart Pro-1 heads
Comp Cam with 268/276 adv duration
LT1 intake
Hooker Headers
Custom Chip from PCMforless
This is my first major engine build that keeps the computer in control.
I can get it to start and run if I advance the initial (computer unplugged) timing to 20 BTDC.
When I set the timing back to the stock 6 BTDC with the computer unplugged and then plug back in, it will not start or idle.
When I degreed the cam it was off by 1 degree but the cam has 4 degrees of advance already built-in so I am at 5 degrees advance on the cam already. This shouldn't effect ignition timing but I thought it might be noteworth.
I also used the L98 throttle body on the LT1 intake. I notice the idle circuit is differant between the L98 and LT1.
I don't believe I have had the engine running long enough for it to got to closed loop yet.
Any ideas................... Can the Idle be adjusted up without a chip change?
thanks in advance for the help.
I have just completed a new engine build with:
L98 bottom end
Dart Pro-1 heads
Comp Cam with 268/276 adv duration
LT1 intake
Hooker Headers
Custom Chip from PCMforless
This is my first major engine build that keeps the computer in control.
I can get it to start and run if I advance the initial (computer unplugged) timing to 20 BTDC.
When I set the timing back to the stock 6 BTDC with the computer unplugged and then plug back in, it will not start or idle.
When I degreed the cam it was off by 1 degree but the cam has 4 degrees of advance already built-in so I am at 5 degrees advance on the cam already. This shouldn't effect ignition timing but I thought it might be noteworth.
I also used the L98 throttle body on the LT1 intake. I notice the idle circuit is differant between the L98 and LT1.
I don't believe I have had the engine running long enough for it to got to closed loop yet.
Any ideas................... Can the Idle be adjusted up without a chip change?
thanks in advance for the help.
Safety Car
Joined: May 2006
Posts: 4,290
Likes: 140
From: Salem NH
Originally Posted by gear-head2
Hi,
I have just completed a new engine build with:
L98 bottom end
Dart Pro-1 heads
Comp Cam with 268/276 adv duration
LT1 intake
Hooker Headers
Custom Chip from PCMforless
This is my first major engine build that keeps the computer in control.
I can get it to start and run if I advance the initial (computer unplugged) timing to 20 BTDC.
When I set the timing back to the stock 6 BTDC with the computer unplugged and then plug back in, it will not start or idle.
When I degreed the cam it was off by 1 degree but the cam has 4 degrees of advance already built-in so I am at 5 degrees advance on the cam already. This shouldn't effect ignition timing but I thought it might be noteworth.
I also used the L98 throttle body on the LT1 intake. I notice the idle circuit is differant between the L98 and LT1.
I don't believe I have had the engine running long enough for it to got to closed loop yet.
Any ideas................... Can the Idle be adjusted up without a chip change?
thanks in advance for the help.
I have just completed a new engine build with:
L98 bottom end
Dart Pro-1 heads
Comp Cam with 268/276 adv duration
LT1 intake
Hooker Headers
Custom Chip from PCMforless
This is my first major engine build that keeps the computer in control.
I can get it to start and run if I advance the initial (computer unplugged) timing to 20 BTDC.
When I set the timing back to the stock 6 BTDC with the computer unplugged and then plug back in, it will not start or idle.
When I degreed the cam it was off by 1 degree but the cam has 4 degrees of advance already built-in so I am at 5 degrees advance on the cam already. This shouldn't effect ignition timing but I thought it might be noteworth.
I also used the L98 throttle body on the LT1 intake. I notice the idle circuit is differant between the L98 and LT1.
I don't believe I have had the engine running long enough for it to got to closed loop yet.
Any ideas................... Can the Idle be adjusted up without a chip change?
thanks in advance for the help.
Closed loop has nothing to do with it. If your IAC is wired wrong, thats you're first problem.
Basicly, you need to do the following (in order)
1) Fix IAC wiring
2) Set base timing to 6 degrees
3) Set min idle speed. (go into diag, unplug iac, turn set screw to 600rpm).
4) Get a laptop, emulator or prom burner, aldl cable and start tuning. Throw the PCMforless chip in the garbage where it belongs.
-- Joe
Melting Slicks
Joined: Nov 2003
Posts: 2,679
Likes: 1
From: South Amboy NJ
Originally Posted by anesthes
Throw the PCMforless chip in the garbage where it belongs.
Safety Car
Joined: May 2006
Posts: 4,290
Likes: 140
From: Salem NH
Originally Posted by BlackRoseLT1
Your first 3 suggestions aren't bad. This one is plainly idiotic. I see that you are on TGO and i've been on there since 2001 and I know all you guys tune but you should respect a great tuner, not say that their chip is garbage. I picked up over a second and 10 mph in the quater mile with a PCMFORLESS tune as well as gained a nice steady idle, great driveability, gas mileage, and ability to rev to 6500 rpm all for $150. Now to get all the things needed to tune yourself you have to spend atleast twice that, if not more, and to gain the knowledge would take even longer.
-- Joe
Melting Slicks
Joined: Aug 2003
Posts: 3,407
Likes: 400
From: Lakeville MI
Talk to Alvin,
Ask him if Cold Spark is enabled.
Cold Spark, if enabled can subtract like 20 degrees of advance until the coolant temp increases 20 degrees over the startup coolant temp.
Ask him if Cold Spark is enabled.
Cold Spark, if enabled can subtract like 20 degrees of advance until the coolant temp increases 20 degrees over the startup coolant temp.
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Originally Posted by BlackRoseLT1
This one is plainly idiotic. I see that you are on TGO and i've been on there since 2001 and I know all you guys tune but you should respect a great tuner, not say that their chip is garbage. I picked up over a second and 10 mph in the quater mile with a PCMFORLESS tune as well as gained a nice steady idle, great driveability, gas mileage, and ability to rev to 6500 rpm all for $150. Now to get all the things needed to tune yourself you have to spend atleast twice that, if not more, and to gain the knowledge would take even longer.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Originally Posted by Lichen
With LT headers, you may need heated O2 sensor(s).
Solved most of my idle probs with mods on account of the headers too cold at idle.
You really need to be able to scan engine so as to see what is going on so people here can sort you problems.
However if you need timing out to 20 BTDC to get it to start figure you may have problems with something else than basic tune.
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